Police have confirmed that at least some of the children – who were aged between 18 months and 15 years – were stabbed during the tragic incident in Cairns.

A 34-year-old woman who was mother to seven of the youngsters is being treated in hospital for serious injuries and is assisting police with their inquiries. The Brisbane Times reports that a second person is also in hospital, but their condition and involvement is unclear.

A 20-year-old brother of the siblings made the grim discovery on Friday morning, AAP reported. The eighth dead child is understood to be a family member.

Cairns Detective Inspector Bruno Asnicar said there were currently no formal suspects, but added that there was no danger to the public.

“As it stands at the moment there’s no need for the public to be concerned about this other than that it’s a tragic, tragic event,” he said. “The situation is well-controlled at the moment.”

Extra police officers are being sent up from Brisbane to join the inquiry. However, police will only move in once forensic experts have completed their examination of the house in Murray Street, in the Manoora area of Cairns.

The incident completes a grim week for Australia following the deaths of two hostages and a gunman in the siege of a café in Sydney on Tuesday.

Prime minister Tony Abbott said in a statement that an “unspeakable crime” had taken place in Cairns.

“All parents would feel a gut-wrenching sadness at what has happened,” said Mr Abbott. “These are trying days for our country. Tonight there will be tears and prayers for these children.”